Graphic display devices generally include a display screen, a display controller, data channels, and an input device(s). There are many types of input devices, some of which are X-Y or X-Y-Z direction input devices, commonly known in the art as "mouse" or "trackball" systems, configured to detect the moving direction and distance of a coordinate indicating ball within a casing.
With respect to "mouse" systems, these X-Y directional input systems generally include a rotatably supported ball made of steel or rubber, a first sensor roller contacting and rotated by the ball, a second sensor roller contacting and rotated by the ball, the second sensor having an orientation perpendicular to the orientation of the first roller. Also included in typical "mouse" systems are first and second rotation detectors connected via shafts to the first and second sensor rollers. Each rotation detector includes a rotary electrical member, such as a variable resistor or an encoder. These detectors independently detect rotation of the above-mentioned first and second sensor rollers which are caused to rotate by movement of the ball.
Typically, "mouse" X-Y or X-Y-Z direction input devices include push switches or buttons, located inside of or along the outside of the casing, to effect deletion or dislocation of patterns or figures displayed on the screen or to enable signal processing for other switching and control operations when activated.
Mouse casings typically include an aperture defined in the bottom thereof so as to allow the ball to project slightly downward. When the casing is moved along a generally flat surface or platform, the ball necessarily rotates on the surface with the first and second sensor rollers being rotated in predetermined different (X or Y) directions respectively. The amounts of rotation of the first and second rollers are independently extracted by the corresponding first and second detectors. The detectors output corresponding voltages or digital signals indicative of the detected X and Y directional components, which are eventually sent to the display apparatus.
With respect to conventional "trackball" devices, such a device is illustrated in prior art FIG. 1(a). "Trackball" devices, such as the one illustrated in FIG. 1(a), perform functions similar to those of the conventional mouse devices described above. In other words, "trackball" devices are also X-Y or X-Y Z coordinate input systems for moving a cursor or the like on a display screen to a desired coordinate point on the screen. Alternatively, they may be used to select desired menu items appearing on the display by way of moving the cursor and activating button(s). Typically, "trackball" devices respond to manual rotation of a ball partly projecting from the upper wall of the casing, with the amount of ball rotation determining the cursor movement.
As shown in prior art FIG. 1(a), typical "trackball" device T includes housing 1 serving as an outer shell provided with circular opening 3 formed in the top wall thereof. Rotatable ball 5 mounted in housing 1 partially projects outwardly through circular opening 3 above the top wall. A pair of sensor rollers or rotatable members 7 and 9 are arranged substantially orthogonal to one another and are rotatable in accordance with rotation of ball 5. Detectors 11 and 13 are connected to rollers 7 and 9 respectively via shafts so as to make up orthogonally oriented rotation sensors. Detectors 11 and 13 are, for example, encoders capable of detecting the amount of rotation of rollers 7 and 9, respectively.
In operation, the user of "trackball" T rotates ball 5 within casing 1. The X-axis component and the Y-axis component of ball rotation are transmitted to the X and Y sensor rotating members 7 and 9 respectively, these components having substantially perpendicular directional vectors. The amount of rotation of rollers 7 and 9 is detected by detectors 11 and 13 respectively, which in turn produce signals in accordance with which a cursor is moved on a display screen (not shown) of a display device to which the "trackball" device is in electrical communication. When the cursor has been moved to a desired coordinate position or to a position of a desired menu item on the display, the user stops rotation of ball 5 and turns or presses an input button switch(es) (not shown), thereby inputting the coordinate value or selecting the menu item.
In the increasingly miniaturized world of computer technology, it is desirable to utilize as little space as possible when designing computer related equipment, including coordinate input devices. Unfortunately, prior art "mouse" and "trackball" devices are rather bulky and take up large amounts of space due to their many components disposed between the ball and the casing exterior.
U.S. Pat. No. 5,379,053 discloses a cursor control device for a computer display. The controller includes a solid member surrounded by a flexible bladder, both being received within a housing. The bladder is freely movable relative to the solid so that its movement is sensed by X and Y transducers to generate signals which may be employed to control the visual display of a computer. The device may be physically connected to the computer or alternatively use a wireless transmitter to broadcast signals to a receiver associated with a computer. Unfortunately, the design of this prior art suffers from at least the following problems. Firstly, the controller is ergonomically undesirable. Secondly, the shape of the solid inner member in corresponding flexible bladder are problematic in that the presence of rather sharp corners is thought to lead to premature wearing of the controller as well as inefficient coordinate input data. Furthermore, the flexibility of the outer bladder of U.S. Pat. No. 5,379,053 may lead to undesirable friction between the two members during movement of them relative to one another.
It is apparent from the above that there exists a need in the art for a "trackball" or "mouse" device which is reduced in size with respect to prior art devices, includes a lesser number of moving parts disposed outside of the ball within the casing, and is not prone to premature wearing or inefficient coordinate input.
It is the purpose of this invention to fulfill the above-described needs in the art, as well as other needs apparent to the skilled artisan from the following detailed description of this invention.